I was recently made aware of this cool thing called Jellyfin! The idea is, it’s a streaming platform designed around each user/family/etc hosting their own media server, which is super awesome!

It’s even available to be installed on linux machines directly from the package manager. Great!

Networking though?

I wanted to expose my instance to the larger internet, so I could let friends use it too!

It started out well and I was able to set up Dynamic DNS on one of my domains easily (because no static IPs for me). This made it possible to ping the machine using its public domain!

But… no other services I tried to talk to would reach the machine. I dug around a while trying to figure out what was happening, slowly exhausting the possible causes:

• no firewalls on my router
• no firewalls on the server
• port forwarding on my router was correct
• the services were listening correctly
• I could access the services using the server’s DHCP address…

But I finally found my answer while searching online. Apparently my ISP uses CGNAT, and offers no way to set port forwarding rules at that level. So what I was trying to do was impossible, at least “the simple way”.

To be continued!